linux-kernel - Re: [PATCH 1/2 v3] mmc: dw_mmc: Fix the DTO timeout overflow calculation for 32-bit systems

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Message-ID: <d955cc19-1398-3c05-4742-32664480d07d@rock-chips.com>
Date:   Tue, 27 Feb 2018 09:14:23 +0800
From:   Shawn Lin <shawn.lin@...k-chips.com>
To:     Evgeniy Didin <Evgeniy.Didin@...opsys.com>,
        linux-mmc@...r.kernel.org
Cc:     shawn.lin@...k-chips.com,
        Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
        Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>,
        Douglas Anderson <dianders@...omium.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        linux-kernel@...r.kernel.org, linux-snps-arc@...ts.infradead.org,
        stable@...r.kernel.org, Vineet Gupta <Vineet.Gupta1@...opsys.com>
Subject: Re: [PATCH 1/2 v3] mmc: dw_mmc: Fix the DTO timeout overflow
 calculation for 32-bit systems


> Tested-by: Vineet Gupta <Vineet.Gupta1@...opsys.com>
> Fixes: ARC STAR 9001306872 HSDK, sdio: board crashes when copying big files
> 
> Signed-off-by: Evgeniy Didin <Evgeniy.Didin@...opsys.com>
> 
> CC: Alexey Brodkin <abrodkin@...opsys.com>
> CC: Eugeniy Paltsev <paltsev@...opsys.com>
> CC: Douglas Anderson <dianders@...omium.org>
> CC: Ulf Hansson <ulf.hansson@...aro.org>
> CC: linux-kernel@...r.kernel.org
> CC: linux-snps-arc@...ts.infradead.org
> Cc: <stable@...r.kernel.org> #  9d9491a7da2a mmc: dw_mmc: Fix the DTO timeout calculation

As I said, the correct tag may be:

Reported-by: Vineet Gupta <Vineet.Gupta1@...opsys.com> # ARC STAR 
9001306872 HSDK, sdio: board crashes when copying big files
Tested-by: Vineet Gupta <Vineet.Gupta1@...opsys.com>
Fixes: 9d9491a7da2a ("mmc: dw_mmc: Fix the DTO timeout calculation")
Cc: <stable@...r.kernel.org>
Signed-off-by: Evgeniy Didin <Evgeniy.Didin@...opsys.com>
...
...


> ---
> Nothing changed since v2.
>   drivers/mmc/host/dw_mmc.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 

> -	drto_ms = DIV_ROUND_UP(MSEC_PER_SEC * drto_clks * drto_div,
> +
> +	drto_ms = DIV_ROUND_UP((u64)MSEC_PER_SEC * drto_clks * drto_div,
>   			       host->bus_hz);
>   

Hmm?

#define DIV_ROUND_DOWN_ULL(ll, d) \
	({ unsigned long long _tmp = (ll); do_div(_tmp, d); _tmp; })

#define DIV_ROUND_UP_ULL(ll, d)		DIV_ROUND_DOWN_ULL((ll) + (d) - 1, (d))


It uses intermediate unsigned long long _tmp for your "multiply", namely
MSEC_PER_SEC * drto_clks * drto_div, which could solves the problem.
So I don't see why DIV_ROUND_UP_ULL can't work for you?


>   	/* add a bit spare time */
>